This invention relates generally to power production, and more particularly concerns use of a two-phase nozzle in a process employing a fluid exhibiting a regressive vapor dome in the temperature-entropy plane.
Conventional vapor turbines operating in systems utilizing waste heat as energy sources encounter a pinch point problem in transferring the energy from the waste heat to the working fluid. The problem is a result of the heat of vaporization that must be absorbed to vaporize the working fluid as shown in FIG. 1, so that the energy can be transformed into shaft work in a vapor turbine. As a result, there always exists a large temperature difference between the temperature of the exhaust gas and the working fluid (see .DELTA.T.sub.pp on FIG. 1). This limits the upper temperature of the working fluid which in turn limits the thermodynamic efficiency of the system.